1. Field of the Invention
This invention relates to centrifuges useful to separate a fluid mixture containing two compounds of different density such as compounds of different molecular weight. The invention is particularly useful for an enrichment separation of compounds in which one compound is present in a gaseous mixture with another compound in an amount of less than 5% for an enrichment by which there is obtained a gaseous product that contains at least a threefold greater concentration of the desired compound in that gaseous product. Thus the invention especially relates to a gas centrifuge useful to separate compounds of a natural mixture of isotopes of a chemical element in which the compounds differ in mass by a small percentage. Such use includes the enrichment of an isotope of uranium in the form of a gaseous uranium compound, e.g., separation of gaseous uranium hexafluoride made from natural uranium that contains less than 1% of U.sup.235 isotope to obtain a gaseous product that is enriched with respect to U.sup.235. From that product there is obtained U.sup.235 -enriched uranium having various uses including neutronic power reactors.
2. Description of the Prior Art
Centrifugal devices or apparatuses for separating solids or immiscible liquids from liquids include drum-type centrifugal clarifiers that are modifications of centrifugal contactors, solid bowl centrifuges, basket-type centrifuges, and continuous disc-type centrifuges.
A description of these types of centrifugal devices is presented in my copending patent application mentioned above. That description is hereby incorporated by reference. The description includes reference to articles in two publications, to Swedish Pat. Nos. 20754 and 20757, to U.S. Pat. Nos. 587,171, 787,950, 2,619,280, 3,027,390, 3,047,215, 3,053,440, 3,202,407, 3,344,982, 3,344,983 and 3,519,199, and to British Pat. Nos. 966,153 and 1,123,958. Two of the U.S. patents and U.S. Pat. No. 3,695,509, along with German Pat. No. 129569, were cited against my copending application mentioned above, but none of these patents and articles disclosed or would suggest a construction of a centrifugal device as claimed in that copending patent application. That claimed centrifugal device has a structure that in many respects is common with the structure of the centrifugal device of the present invention.
As pointed out in the article entitled "Enriching Europe with the gas centrifuge" in the Oct. 5, 1972, issue of New Scientist a gas centrifuge has been developed in Europe for the enrichment of uranium fuel. The construction of the centrifuge is not stated except to indicate that it is a centrifuge cascade and needs only 20-30 stages to obtain a product containing a typical 2.9% content of U.sup.235. It is indicated in the article that the separation factor is increased by the 3rd and 4th power of the peripheral speed. Gas centrifuges are described at pages 21-55 in Uranium Enrichment by Gas Centrifuge by D. G. Avery and E. Davies, published in 1973 by Mills & Boon Limited, London, England.